Buses are widely used in information handling systems for exchanging information between parts of the systems. There exist two types of buses: synchronous buses and the asynchronous buses. The exchange of information through asynchronous buses is controlled by handshaking protocols which slows the thruput. In addition they require a relatively high number of wires.
The exchange of information through synchronous buses is controlled through specific data frame arrangements.
Direct memory access is a feature which is frequently used in information handling systems.
Now, for example, in an information handling system such as a communication controller the capability of connecting high speed lines through high speed line adapters such as described in European Patent Application No. 86430015.7 filed on Apr. 30,1987 is now offered. In such type of controllers, a direct memory access bus comprises the direct path which allows information to be read from and written into the memory by the line adapters in order to send or receive information from the high speed lines. For improving the operation of the communication controller, improving this path is highly desirable.